Device for recirculating the exhaust gas of an internal combustion engine

ABSTRACT

A device for recycling exhaust gases from an internal combustion engine via an exhaust gas line in its intake area is equipped with an exhaust gas valve that is positioned within a valve chamber and closes off or opens up the connection to a combustion chamber of an internal combustion engine. A valve actuating mechanism is located within the valve chamber. The valve chamber is equipped with at least one cooling channel.

BACKGROUND OF THE INVENTION

The present invention relates to a device for recycling exhaust gas froman internal combustion engine.

A device of the type mentioned above is described in EP 0 887 340 A2. Inthis design, a cooling channel for cooling the system is provided withinthe valve chamber, which encircles the valve guide like a ring and isconnected to the cooling system of the internal combustion engine.

To prevent a valve stem or valve spindle and the a valve stem guide frombecoming fouled, a bushing arrangement is known from German publicationDE 196 37 078 A1, in which a bushing is provided around the valve stem.This bushing serves to protect the valve stem guide against thermalradiation and contamination. The effectiveness of this bushingarrangement, however, is limited.

In German publication DE 44 24 644 C1, an exhaust gas recycling valvecomprising a valve socket that is positioned within an intake channeland serves to carry the exhaust gas is described. The valve socket isenclosed by a highly thermally conductive flange, which serves toabstract high levels of heat from the hot exhaust gas, thereby allowingmore cost-effective injection-molded plastic components to be used inthe exhaust gas recycling system.

As is apparent from the current state of the art, devices of the typementioned above present problems in terms of temperature. On one hand,the exhaust gas valve should be positioned as close as possible to thepoint at which exhaust gas exits the internal combustion engine, inorder to prevent cooled exhaust gases from accumulating as a result ofcarbonization of the exhaust gas particles, a condition that wouldinterfere with the functioning of the valve. On the other hand, the highexhaust gas temperatures that are required to prevent carbonizationrequire components that are sufficiently heat-resistant, and hencecost-intensive. Furthermore, actuating the exhaust gas valve via anelectromagnetic actuating mechanism, which is positioned within thevalve chamber, presents a temperature problem for certain components.Due to the danger of carbonization, greater actuating forces must beused, which then require more costly components.

It is thus one object of the present invention to provide a device ofthe type mentioned above, with which higher exhaust gas temperatures andan effective outflow of exhaust gases can be achieved.

With an exhaust gas collection chamber according to the invention, fromwhich the exhaust gas return line branches, an effective, low-frictionoutflow of exhaust causes can be attained.

This and other things are achieved via a spherical shape, which resultsin lower flow losses, and thus low friction losses.

Another possibility for generating low flow losses is to connect thefunnel-shaped exhaust gas return line to the spherical exhaust gascollection chamber. In this manner, an angle-free, and thuslow-friction, flow can be achieved.

In accordance with the invention, the valve seat of the exhaust gasvalve can have a stepped contour, such that when the valve is opened, atleast two different angles of aperture are created, with a smaller anglebeing produced when the valve is first opened.

Because the valve seat for the exhaust gas valve has a stepped contourin accordance with the invention, when the valve is opened, the smallerangle of aperture at the start of exhaust gas recycling permitssignificantly improved control, and thus a metered recycling of exhaustgases, with a corresponding degree of sensitivity.

Additional advantageous embodiments and further developments arespecified in the claims, relating to the exemplary embodiment describedin principle below, with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section, along the line I—I in FIG. 2, of avalve chamber in an exhaust gas recycling valve,

FIG. 2 is a longitudinal section, along the line II—II in FIG. 1, of avalve chamber in an exhaust gas recycling valve,

FIG. 3 is a cross-section, along the line III—III in FIG. 2, of a valvechamber in an exhaust gas recycling valve,

FIG. 4 is a perspective view of the valve chamber, and

FIG. 5 is an enlarged representation of the valve seat and the lowersection of the valve.

Additional advantageous embodiments and further developments arespecified in the claims, relating to the exemplary embodiment describedin principle below, with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section, along the line I—I in FIG. 2, of avalve chamber in an exhaust gas recycling valve,

FIG. 2 is a longitudinal section, along the line II—II in FIG. 1, of avalve chamber in an exhaust gas recycling valve,

FIG. 3 is a cross- section, along the line III—III in FIG. 2, of a valvechamber in an exhaust gas recycling valve,

FIG. 4 is a perspective view of the valve chamber, and

FIG. 5 is an enlarged representation of the valve seat and the lowersection of the valve.

DETAILED DESCRIPTION OF THE INVENTION

In a valve chamber 1, an exhaust gas valve 2 comprising a valve stem 3and a valve head 4 at its forward end is positioned within a valve guide5 that encompasses the valve stem 3. The valve head 4 of the valve 2operates in conjunction with a valve seat 6 within the valve chamber 1,which is formed by an insertion sleeve 7. Below, the design of theinsertion sleeve 7 (illustrated only in FIG. 1) will be described ingreater detail.

Exhaust gas from the outlet point of an internal combustion engine, notillustrated here, flows in the direction A into the valve chamber 1, andis collected in a spherical exhaust gas collection chamber 8 when thevalve 2 is open. An exhaust gas return line 9 branches off from theexhaust gas collection chamber 8. The exhaust gas return line 9 isfunnel-shaped, and is attached along the center plane of the sphere onits outer wall, resulting in a low-friction flow from the exhaust gascollection chamber 8.

As can be seen from the exhaust gas valve, which for purposes of clarityis shown only in FIG. 1, the valve stem 3 is covered by a cap 10. Theposition of the cap 10, which follows the movements of the exhaust gasvalve 2, is such that when the valve is opened—as is shown in FIG. 1—theunderneath side of the cap is nearly flush with the wall of the exhaustgas collection chamber 8, producing an angle-free shape to the wall ofthe exhaust gas collection chamber, thus preventing flow losses thatcould be caused by protruding edges or by recesses.

As can be seen in FIGS. 1 and 2, the valve chamber 1 is equipped with acooling channel 11 in the area of the valve guide 5, with this coolingchannel encircling the valve guide 5 like a ring, effectively reducingthe temperature inside the valve chamber, without requiring an increasein its dimensions. The flow into the cooling channel 11 is effected viaa connecting branch 12. The connecting branch 12 is connected to thecooling system of the internal combustion engine in a manner notillustrated here—as is a return line, also not illustrated here.

In the known manner, an uptake chamber 13 is positioned above the valveguide, or on the side of the valve chamber that faces away from thevalve head 4, and houses actuating mechanisms 14 for the exhaust gasvalve, which in FIG. 1 are illustrated only schematically.

As is shown here, the uptake chamber 13 for the actuating mechanism 14is well protected by the cooling channel 11 against the hightemperatures of the exhaust gas that enters the valve chamber 1. Thismakes it possible for the valve chamber 1 to be positioned very close tothe internal combustion engine, or even flange-mounted to the internalcombustion engine via a mounting flange 18, which keeps the exhaust gastemperature within the valve chamber 1 high enough to preventaccumulation on the valve stem, which could otherwise interfere with thefunctioning of the valve. In this manner also, no major actuating forcesare required for opening and closing the exhaust gas valve 2, hence theactuating mechanism 14 can be designed to be more cost-effective.

As can be seen in FIG. 5, the valve seat 6 or the insertion sleeve 7which forms the valve seat 6, has a stepped contour. A first step 15conforms with the peripheral wall of the valve head 4 such that a closedposition, and thus a sealing off of the exhaust gas collection chamber8, is achieved. In a second step 16—created as the exhaust gas valve 2is opened—the angle of aperture that is produced is smaller than with athird step 17, in which the exhaust gas valve 2 is fully opened. Theangle of aperture for the second step 16 may be, for example, 15° fromthe longitudinal axis of the exhaust gas valve 2, while the angle ofaperture for the third step may, for example, be 40° from thelongitudinal axis of the exhaust gas valve 2. The two steps 16 and 17,with their different angles of aperture, allow a particularly sensitivecontrol of the quantity of recycled gas, especially when the valve ispartially opened.

In contrast to the exemplary embodiments illustrated in the diagrams, analternative or supplemental elimination of heat from the valve chambercan be achieved via the creation of heat bridges from the chamber to thesurrounding components, for example via contact surfaces. These may bedesigned as a mounting flange that is larger than the mounting flange 18illustrated in FIG. 1, which would then be mounted flat or pressedagainst (large) opposing surfaces of the engine casing. It isparticularly advantageous for the contact surfaces to be arranged alongcooled opposing surfaces of the engine casing, such as surfaces of thecylinder head.

In accordance with a further embodiment, in addition to or in place ofthe above-described measures, the heat that is within the exhaust gasrecycling valve may be emitted into the environment via cooling gills.These are preferably positioned in the area of the exhaust gascollection chamber 8 and/or within the cooling channel 11.

What is claimed is:
 1. A device for recycling exhaust gas from aninternal combustion engine via an exhaust gas return line in an intakechannel of the internal combustion engine, comprising: an exhaust gasvalve positioned within a valve chamber, provided with a valve head, anddesigned to seal off or open up a connection to a combustion chamber ofthe internal combustion engine; a valve actuating mechanism positionedwithin the valve chamber; at least one cooling channel, and an exhaustgas collection chamber, which is at least nearly spherical in shape,positioned behind the valve head of the exhaust gas valve, the exhaustgas return line being connected to the exhaust gas collection chamber.2. The device in accordance with claim 1, wherein the exhaust gas returnline is funnel-shaped, and wherein the exhaust gas return line isconnected to the exhaust gas collection chamber.
 3. The device inaccordance with claim 1, wherein the exhaust gas valve has a valve stemcovered by a cap, which, when the exhaust gas valve is open, lies atleast nearly flush with a peripheral wall of the exhaust gas collectionchamber.
 4. The device in accordance with claim 1, wherein the exhaustgas valve has a valve seat which is stepped such that, when the valve isopened, at least two different angles of aperture are possible, with asmaller angle of aperture being created when the valve is first opened.5. The device in accordance with claim 4, wherein the valve seatproduces two different angles of aperture.
 6. The device in accordancewith claim 5, wherein a first angle of aperture is in a range from 10°to 20°, and a second angle of aperture is in a range from 30° to 50°. 7.The device in accordance with claim 4, wherein the stepped valve seathas a contour which is formed by an insertion sleeve positioned withinthe valve chamber.
 8. The device in accordance with claim 2, wherein theexhaust gas valve has a valve stem covered by a cap, which, when theexhaust gas valve is open, lies at least nearly flush with a peripheralwall of the exhaust gas collection chamber.
 9. The device in accordancewith claim 2, wherein the exhaust gas valve has a valve seat which isstepped such that, when the valve is opened, at least two differentangles of aperture are possible, with a smaller angle of aperture beingcreated when the valve is first opened.
 10. The device in accordancewith claim 3, wherein the exhaust gas valve has a valve seat which isstepped such that, when the valve is opened, at least two differentangles of aperture are possible, with a smaller angle of aperture beingcreated when the valve is first opened.
 11. The device in accordancewith claim 10, wherein the valve seat produces two different angles ofaperture.
 12. The device in accordance with claim 11, wherein a firstangle of aperture is in a range from 10° to 20°, and a second angle ofaperture is in a range from 30° to 50°.
 13. The device in accordancewith claim 5, wherein the stepped valve seat has a contour which isformed by an insertion sleeve positioned within the valve chamber. 14.The device in accordance with claim 6, wherein the stepped valve seathas a contour which is formed by an insertion sleeve positioned withinthe valve chamber.
 15. The device in accordance with claim 9, whereinthe valve seat produces two different angles of aperture.
 16. The devicein accordance with claim 15, wherein a first angle of aperture is in arange from 10° to 20°, and a second angle of aperture is in a range from30° to 50°.
 17. The device in accordance with claim 16, wherein thestepped valve seat has a contour which is formed by an insertion sleevepositioned within the valve chamber.